Field of the Invention
The present invention relates to a method for manufacturing a solid-state image pickup apparatus, the solid-state image pickup apparatus, and an image pickup system including the solid-state image pickup apparatus.
Description of the Related Art
In recent years, a configuration equipped with a global electronic shutter function has been proposed for active-pixel solid-state image pickup apparatuses represented by complementary metal-oxide semiconductor (CMOS) image sensors.
Such a solid-state image pickup apparatus equipped with the global electronic shutter function includes a light receiving unit that carries out photoelectric conversion, and a charge holding unit that holds a charge generated from the photoelectric conversion at the light receiving unit. At this time, if light is incident on the charge holding unit and the photoelectric conversion is carried out there, a noise signal may occur, leading to deterioration of an image quality. Therefore, the charge holding unit should be covered with a light shielding film to prevent the light from being incident thereon.
The solid-state image pickup apparatus having the light shielding structure includes an optically transparent insulating film between a substrate and the light shielding film, whereby a light shielding performance is improved by preventing the light from entering from this insulating film.
Japanese Patent Application Laid-Open No. 2014-22421 discusses improving coatability of the light shielding film on a side portion of a gate electrode by forming the light shielding film after forming the gate electrode and the side wall.
On the solid-state image pickup apparatus including a transistor with the side wall formed below the light-shielding film on a pixel unit, an exposed semiconductor region may be damaged by etching when the side wall is formed after the gate electrode is formed.